As seen in FIG. 1, currently optical modules 1, including transmitters, receivers and transceivers, are packaged in metal or ceramic boxes 5. Alignment between the optical fibre 16 disposed in V groove of a silicon optical bench 18 and an active optical element 14 is achieved using an active optical alignment process implemented during the assembly of the receiver module. The V groove fibre 16 is then coupled to a further fibre 10 located in a ferrule 12 attached to an aperture 7 at one end on the module.
As use of the Internet and optical fibre based communication increases, there is a growing need for faster transmission rate. Transmission rates of 10 Gb/s are becoming common and this is set to increase in the near future to 40 Gb/s and beyond.
In addition, there is a constant effort among network and communication system providers to drive down the cost of the systems, which means both component and transceiver module manufacturers must reduce the cost of their product in order to remain competitive.
An active alignment process in which the fibre is moved into position with respect to the active optical element while the element is powered is both labour intensive and time consuming, and thus expensive and not in-line with current industry efforts to reduce the cost of optical module packages.
Furthermore, due to the small size of the active area of high-speed components, such as a 10 Gb/s photodiode, very precise alignment must to be achieved between the fibre and the photodiode in order to maximize coupling efficiency. For example, a fibre placed 50 um from a photodiode will need to be placed with a 5 um tolerance in the transversal plane and a 10 um tolerance on longitudinal axis.